Method of making a grooved mold

ABSTRACT

This invention deals with a method for producing a mold member having a plurality of helical molding grooves. Endless grooves are formed on the surface of a mold blank which is then divided along a line which intersects each endless groove twice. The divided mold blank segments are then aligned in such a way as to define a plurality of helical grooves.

United States Patent [72] inventors AlvinJ.Furstenburg Chicago; EdmundJ. Kujawa, Wilmette, Ill. {21 Appl. No. 745,056 [22] Filed Apr. 10,1968

Division of Ser. No. 542,343, Apr. 13, 1966, Pat. No, 3,406,430. {45]Patented May 25, 1971 [73] Assignee Felt Products Mfg. Co.

[54] METHOD OF MAKING A GROOVE!) MOLD 9 Claims, 21 Drawing Figs.

[52] US. Cl 29/416, 29/425, 18/42, 249/59, 264/219 [51] Int. Cl 323p17/00,

[50] Field of Search 264/320, 219, 106, 107; 29/464, 415, 416, 425',l8/(lnquired), 36, 42, 44; 249/59; 113/1 16 (BB); 10 l/401.1

[56] References Cited UNITED STATES PATENTS 3,288,900 11/1966 Morin264/320 2,148,079 2/1939 Martin 18/Flash 3,357,056 12/1967 Reyburn 18/42Primary Examiner-Robert F. White Assistant Examiner-Richard ShearAttorney-Dressler, Goldsmith, Clement and Gordon ABSTRACT: Thisinvention deals with a method for producing a mold member having aplurality of helical molding grooves. Endless grooves are formed on thesurface of a mold blank which is then divided along a line whichintersects each endless groove twice. The divided mold blank segmentsare then aligned in such a way as to define a plurality of helicalgrooves.

METHOD OF MAKING A GROOVED MOLD This application is a division of ourapplication Ser. No. 542,343, filed Apr. 13, 1966 now US. Pat. No.3,406,430.

This invention relates to a compact mold for molding elongated strips ofmaterial, such as gasketing material, of uniform quality throughouttheir lengths, and to methods of making and using said mold.

Although the mold of the present invention may be used for moldingvarious types of strip material, the invention will be described withparticular reference to strips of gasketing material in which uniformlyhigh quality throughout the length of the strip is an importantrequirement.

Gasketing material, which may be of rubber or other suitable moldablecomposition, has heretofore been made in desired lengths by extrusionprocesses, by core-molding processes and the like. Extrusion processesare not satisfactory for making gasketing material for many applicationsbecause they do not insure the uniformity of quality that is sometimesrequired throughout the length of the strip in order to obtain suitableand effective seals. Elongated strips of gasketing material produced bycore-molding apparatus may be of unifomily high quality throughout theirlengths. However, the making of molding apparatus of the core-moldingtype is difiicult, elaborate and expensive. The utilization ofcoremolding apparatus results in extremely high labor costs.

In accordance with the present invention, a mold member is provided witha helical molding groove. The helical molding groove and theconvolutions thereof lie in a generally flat plane. That contrasts tocore molds in which the molding groove lies generally in a cylindricalplane. Such a mold has many advantages, among which are its ease ofmanufacture, its ease of utilization in molding, resulting in low laborcosts and the uniformity of the product which may be made in such amold.

This invention concerns itself not only with the mold itself, but alsowith methods 'of making such a mold and the manner of utilizing such amold. Those additional aspects of this invention, together with theiradvantages, will be apparent from the foregoing, and from the followingdescription and drawings of which:

FIG. I is a plan view of a mold blank of a preferred embodiment of thisinvention;

FIG. 2 is a planview of the mold blank of FIG. I with grooves machinedtherein;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a plan view of a completed mold incorporating the mold blankof FIGS. 1 and 2, withportions of the upper mold member broken away toshow the helical configuration of the grooves;

FIG. 5 is an enlarged fragmentary view of a portion of FIG. 3;

FIG. 6 is a fragmentary view similar to FIG. 5 taken along the line 6-6of FIG. 4;

FIG. 7 is an enlarged cross-sectional view taken along the line 7-7 ofFIG. 4;

FIG. 8 is an enlarged fragmentary perspective view viewed generally fromthe line 7-7 of FIG. 4;

FIG. 9 is a plan view of a mold blank of a modification of thisinvention;

FIG. 10 is a plan view of the mold blank of FIG. 9 after grooves havebeen machined therein;

FIG. 11 is an enlarged sectional view taken along the line 11-11 of FIG.12 with an upper mold member overlying the grooves in the mold blank;

FIG. I2 is a plan view of a helical mold member made from the mold blankof FIG. 10;

FIG. 13 is a plan view of a mold blank of a further modification of thisinvention;

FIG. 14 is a plan view of the mold blank of FIG. I3 with groovesmachined therein;

FIG. 15 is a plan view of a helical mold member made from the mold blankof FIG. 14;

FIG. 16 is a plan view of a mold blank of a further modification of thisinvention;

FIG. 17 is a plan view of a further mold blank similar to FIG. 16;

FIG. 18 is a plan view of the mold blank of FIG. 16 with groovesmachined therein;

FIG. 19 is a plan view of the mold blank of FIG. 17 with groovesmachined therein;

FIG. 20 is a plan view of a helical mold member made from portions ofthe mold blanks of FIGS. 18 and 19; and

FIG. 21 is a plan view of a helical mold member made from portions ofthe mold blanks of FIGS. 18 and 19.

As stated, this invention contemplates the provision of a helicallygrooved mold having a groove comprising a plurality of convolutions inwhich the plurality of convolutions lie in a generally flat plane. Inthe embodiments illustrated one of the mold members is made of two ormore sections each defining a plurality of groove segments, saidsections and groove segments being aligned to define one or morecontinuous helical grooves each having a plurality of convolutions.

Referring first to FIGS. 1 to 8 of the drawings, which comprise apresently preferred embodiment of this invention, a mold blank 10 isprovided. Mold blank 10 comprises two abutting mold segments 12 and 14,respectively, abutting adjacent edges 16 and 18 defining a line ofdivision therebetween. Mold segments 12 and 14 are held in abuttingrelationship by a plurality of removable pins 20 which reach downwardlyinto retaining plate 22.

A plurality of grooves are then machined into the generally flatcoplanar surfaces 24 and 26 of abutting mold segments 12 and I4. Thegrooves may be machined into those surfaces initially, or they may bemachined after an annular recess, such as recess 28 best seen in FIG. 3,has been machined.

, As seen in FIGS. 2 and 3, two sets of grooves are machined into therespective surfaces 24 and 26 of the mold segments. The grooves ofgreater cross-sectional area are the molding grooves and are designatedas 30. Adjacent each side of each molding groove there is machined anoverflow groove 32 which, as best seen in FIGS. 3 and 5, is ofsubstantially lesser cross-sectional area than molding grooves 30. I

As seen in FIG. 2, the molding and the overflow grooves are concentricabout a center lying along a line of division provided by abutting edgesI6 and 18. The overflow grooves are substantially uniform incross-sectional area throughout and the molding grooves are ofsubstantially uniform cross-sec; tional area throughout. The moldinggrooves are equally spaced from each other adjacent abutting edges l6,l8, and the overflow grooves are equally spaced from each other adjacentabutting edges 16, 18. As seen in FIG. 2, each overflow groove 32 andeach molding groove 30 is continuous and endless.

After the molding and overflow grooves have been machined in thesurfaces of the abutting mold segments, pins 20 in abutting mold segment14 are removed. Mold segment 14 is then separated form mold segment 12along the line of division defined by the abutting edges. At that timeeach mold segment defines groove segments, each groove segment havingtwo ends opening at the line of division or abutting edge. The ends ofthe groove segments of one mold segment are then brought into alignmentwith the ends of formerly adjacent groove segments of the other moldsegment to provide intercommunication therebetween. That is done forboth molding groove and overflow groove segments.

In that manner, as best seen in FIG. 4, a helical groove configurationis provided. As seen in FIG. 4, two parallel helical molding grooves Mand M are provided, each having a plurality of convolutions. Each isalso provided with an adjacent parallel overflow groove 0 and 0'. Oncethe ends of the grooves have been properly aligned and the respectiveabutting edges l6, 18 of the abutting mold segments are in firmabuttingcontact with each other, additional pins 20 are provided insuitable openings in the mold segments and retaining plate to secure theabutting mold segments to the retaining plate 22 to provide, if desired,a permanent connection therebetween. However, the pins may be removable.

As seen in FIG.'3, recess 28 is circumscribed by vertical walls 34. Whenthe abutting mold segments of FIG. 2 are juxtaposed to define thecontinuous helical grooves just described, wa ls 34 of the two abuttingmold-segment recess sections will no longer be in alignment adjacentedges 16 and 18. Since, in this embodiment, the molding and overflowgrooves have been shown to be positioned within recess 28, to provideconveniently an upper mold member 36 (see FIG. 7) it is desirable toremachine the juxtaposed segments of recess 28 to define a continuouscircular annular recess 28 to receive a complementary mating moldingsection 37. As best seen in FIG. 7, recess 28' has been remachined toprovide generally vertical recess walls 34 and generally helical landareas 40. Recess 28', as seen in FIG. 7, receives complementary moldingsection 37 which, like recess 28', is a continuous annulus. Moldingsection 37 defines a generally flat or planar molding face 42 which,with the molding grooves defines closed helical molding apertures.

Upper mold member 36 may be reciprocably supported as by rods 44 toelevate upper mold member 36 and to bring upper mold member 36 intomating relationship with the mold member constructed as described.Compressive forces may be applied as desired and necessary through meanssuch as a pressure plate, a flat steam platen or by any other well-knownmeans. Additionally, means (not shown) for heating the mold, as a flatsteam platen, may be provided in any conventional manner where necessaryor desirable.

As best seen in FIGS. 5 and 8, the mold of this invention may be used bypositioning a moldable material over and along the continuous helicalmolding grooves M and M. The moldable material may comprise one or moreelongated strips such as ropes 46 of a composition such as anunvulcanized rubber composition which is simply laid over and along themolding grooves manually. The volume of the rope is slightly greaterthan the volume of the molding grooves M and M so that when compressiveforces are exerted against the rope it will fill not only the moldinggroove, but the excess will overflow into the overflow grooves O and O.This assures the proper and desired quality of the strip to be molded inthe mold. The representative distribution of the material of the ropeduring curing and after molding is illustrated by FIG. 6 in which theproduct P is shown in a molding groove and the excess material is shownas E in an overflow groove. Thereafter the mold is opened and product Pand excess E are removed and separated.

As will be appreciated, the configuration of product P may vary asdesired simply by machining molding grooves of differing cross-sectionalareas and configuration in molding segments l2 and 14. Additionally, themolding grooves and/or overflow grooves may be provided in part in thelower mold member and in part in the upper mold member such as in themanner described for providing the grooves in the lower mold memberhereinbefore, and, as illustrated by FIG. 11, the molding and overflowgrooves may be machined in the planar or flat surfaces of abutting moldsegments rather than in a recess of abutting mold segments.

A further embodiment of this invention is illustrated by FIGS. 9 to 12inclusive. There lower mold member 100 comprises mold segments 102, 104and 106. In FIG. 9 mold segments 102 and 104 are shown as being adjacenteach other and abutting each other along an angled division line 108,which division line is defined by abutting edges of mold segments 102and 104. Segments 102 and 104 may be secured to a retaining plate (notshown) in a manner similar to that described in connection with theembodiment of FIG. 1 prior to grooving.

While so retained, mold segments I02 and 104 are provided withcontinuous endless circular concentric molding and overflow grooves 110and 112, respectively, their centers lying on line 108 at theintersection of its angled legs. After the grooves have been suitablymachined in segments I02 and 104, those mold segments are separatedalong line of division I08 and realigned, and mold segment 106 which maybe characterized as an insert or bridging piece is positionedtherebetween. Segment 106 is provided with machined molding and overflowgrooves having the same dimensions and spacing (at their ends) as thoseof the segments 102 and 104. As seen in FIG. 12, the groove segments atthe left-hand side of segment 106 interconnect the former abutting endsof the respective groove segments of mold segments 102 and 104 alongline of contact 108 and 108". However, at the right-hand side of FIG.12, it will be seen that the groove segments of mold segment 106interconnect the ends of formerly adjacent groove segments, therebydefining a single continuous helical molding groove M and an adjacentsingle helical overflow groove 0.

The angle of division line 108 and the relative size and proportions ofmold segment 106 may be varied. In the embodiment illustrated theintersection of the groove segments of mold segment 106 and those ofsegments 102 and 104 is closely tangential, as seen in FIG. 12, asometimes desirable feature.

As seen in FIG. 11, a covering mold member 114 covers the groovedsurface of lower mold member 100. It will be noted that grooves 110 and112 have been machined directly into the planar or flat surface of moldsegment 102 and a molding groove configuration appears in the lower flator planar surface of mold member 114. That molding groove configuration116 may be provided in mold member 114 in the same manner described formaking mold member 100. The overflow groove of mold member 100 may servefor both molding grooves, or overflow grooves may also be provided inmold member 114. When mold members 100 and 114 are juxtaposed theydefine a closed helical molding aperture having a plurality ofconvolutions, part of the molding aperture lying within each of the moldmembers.

Referring now to the embodiments of FIGS. 13 to 15, a lower mold membercomprises flat surfaces plate 152 and bridging segment 154. Plate 152 isdivided into two mold segments 156 and 158 along an angled division line160 having two legs 162 and 164 which intersect at right angles.

A plurality of concentric, endless circular molding and overflow grooves166 and 168, respectively, are then machined in plate 152, theintersection of legs 162 and 164 serving as the radius of the grooves.They are equally spaced from each other along the line of division 160.

Thereafter, section 156 is moved laterally along leg 164 an amount equalto the distance D between the ends of adjacent grooves at the line ofdivision 160. In so doing, as best seen in FIG. 15, the ends of theoverflow and molding grooves of mold segment 156 are moved transverselyinto confronting relationship with the next adjacent molding andoverflow grooves of mold segment 158. In that manner the groove ends arealigned.

Bridging plate or mold segment 154 which has molding and overflowgrooves machined therein is then positioned in the gap between thealigned faces of segments 156 and 158 where they have been separatedalong leg 162 of angled line 160. The grooves of mold segment 154interconnect the aligned spaced ends of the segments of grooves 166 and168, respectively, thus transforming the plurality of circular moldinggrooves and circular overflow grooves into single continuous helicalgrooves M and O.

A covering mold member for the embodiment of FIGS. 13 to 15 may be madeas previously described and the mold used as hereinbefore described.

It is to be noted that the mold member so far described has been madefrom mold blanks comprising a plurality of separable members, i.e.separate mold segments positioned in abutting relationship and thengrooved. Thisprovides very accurately machined abutting edges in theassembled helical molds, something which is not as easy to attain if theblank is first severed after the grooves have been machined. However, itis possible to start with a one-piece mold blank, machine the groovesand then divide the blank into several segments as by sawing or thelike. In either case the segments are separated along a line of divisionto make a mold of embodiments of this invention illustrated herein.

ternate circular molding and overflow grooves 212 and 214 are machinedin the flat coplanar surfaces of segments 204 and 206, while thesesegments are held with their edges in abutting relationship in a mannersimilar to that described in connection with the embodiments of FIGS. 1m8. Grooves 212 and 214 are concentric about a center 216 which lies onthe division line along which the mold segments 204 and 206 abut.Similar y, molding grooves 218 and overflow grooves 220 are machined inthe flat coplanar surfaces of segments 208 and 210 of molding member202, said grooves being concentric about a center 222 which lies on thedivision line along which mold segments 208 and 210 abut.

As with previous embodiments, the molding grooves are equidistantlyspaced from each other at the division lines and the overflow groovesare equidistantly spaced from each other at the division lines. In thisembodiment, that spacing between the molding grooves (spacing D) and theoverflow grooves (spacing X) of mold blanks 200 and 202 is the same.However, the distances of ends of the molding and overflow grooves fromeach other in mold members 200 and 202 is not the same, that differencebeing equal to the distance D or X (both of which are the same) betweenthe molding grooves or the overflow grooves at the division line. Thedistance between the groove ends referred to is the distance between thecenters of the molding grooves or between the centers of the overflowgrooves, both being the same since both are equally spaced from eachother. Thus, as seen in FIGS. 18 and 19, A=B+X.or B-l-D. A being thedistance between the ends of molding groove segments of mold blank 200,B being the distance between the ends of molding groove segments of moldblank 200 and X and D being as described. This is graphicallyillustrated in FIGS. 20 and 21.

When one of mold segments 204 and 206 is aligned with one of moldsegments 208 and 210, a single helical molding groove 224 and a singlehelical overflow groove 226 is provided as seen in FIGS. 20 and 21 bythe aligned and interconnected ends of the respective groove segments.The resulting mold members may be used with a flat surface covering moldmember as previously described or, since they are complementary, theymay be used together to define a helical molding tunnellike groove inwhich said groove lies partially within the surface of each mold member.

The molding grooves and overflow grooves have been illustrated as beingalternate and adjacent in the embodiments described. However, it ispossible, where desired, to provide blank, dividing said mold blank intosegments along said line connecting divided mold blank segments and thedivided land areas between them which land areas will not interfere withthe operation or manufacture of the molds as long as the spacing of thegrooves, both molding and overflow, is proportioned so that when moldsegments are aligned appropriate ends of the groove segments of the moldsegments are aligned or alignable to provide one or more helical grooveshaving a plurality of convolutions.

The foregoing embodiments of this invention are intended to beillustrative only and not limiting on this invention.

We claim:

1. A method of making a molding member defining a continuous helicalmolding groove having a plurality of convolutions, the convolutions ofsaid helical molding groove lying in a generally flat plane, comprisingthe steps of providing a mold blank having a substantially flat surfaceportion, forming in said surface portion a plurality of endless grooves,each of said grooves being of substantially uniform cross-sectionaldimensions and each of said grooves being equidistantly spaced from eachadjacent groove along a line of division of said mold endless groovesegments thereof to define-at least one continuous helical moldinggroove having a plurality of convolutions which lie in a generally flatplane.

2. The method of claim 1 in which said mold blank is divided along aline which divides said endless grooves into equal halves and in whichthe mold blank segments carrying said equal halves are interconnected inabutting contact with each other along said dividing line to define saidcontinuous helical molding groove.

3. The method of claim I in which a mold insert defining groove segmentsin a surface thereof is positioned in abutting contact with said moldblank segments and the groove segments thereof are aligned andinterconnected with said mold blank groove segments to define saidcontinuous helical molding groove.

4. The method of claim I in which said mold blank comprises at least twomold segments having coplanar surface sections defining saidsubstantially flat surface portion, said segments abutting each otherprior to forming said plurality of endless grooves, said mold segmentsbeing separated after groove forming to divide said plurality of endlessgrooves into said groove segments.

5. The method of claim 2 in which said interconnected divided groovesegments define two continuous helical molding grooves.

6. A method of making a molding member definingacontinuous helicalmolding groove, the convolutions of said helical molding groove lying ina generally flat plane, comprising the steps of providing a mold blankhaving a substantially flat surface portion, forming in said surfaceportion a plurality of concentric circular molding grooves, each of saidmolding grooves being of substantially uniform cross-sectionaldimensions and each of said grooves being equidistantly spaced from eachnext adjacent molding groove, dividing said moldblank into segmentsalong a line of division which intersects each of said concentriccircular molding grooves twice to divide said circular molding groovesinto groove segments, and aligning and interconnecting divided moldblank segments and said divided groove segments to define at least onecontinuous helical molding groove having a plurality of convolutionswhich lie in a generally flat plane.

7. The method of claim 1 in which prior to the dividing of said moldblank a second plurality of endless grooves are formed in said surfaceportion, two of said second grooves being positioned adjacent each ofsaid first plurality of grooves.

8. A method of making a molding member defining a continuous helicalmolding groove the convolutions of which lie in a generally flat plane,comprising the steps of fon'ning a first mold segment defining aplurality of open-ended first groove segments, said first groovesegments being equally spaced from each other at adjacent open ends,forming a second mold segment defining a plurality of open-ended secondgroove segments, said second groove segments being equally spaced fromeach other at adjacent open ends, said spacing being the same as thespacing of adjacent ends of said first groove segments, the distancebetween the ends of a groove segment of the first mold segment beingdifferent from the distance between the ends of a groove segment of saidsecond mold segment, that difference being equal to the spacing betweenadjacent open ends of said groove segments, abutting said mold segments,and aligning the ends of the respective groove segments of said moldsegments, whereby a continuous helical molding having a plurality ofconvolutions is made.

9. The method of claim 8 wherein a continuous helical overflow groove isformed adjacent to said continuous helical molding groove.

1. A method of making a molding member defining a continuous helicalmolding groove having a plurality of convolutions, the convolutions ofsaid helical molding groove lying in a generally flat plane, comprisingthe steps of providing a mold blank having a substantially flat surfaceportion, forming in said surface portion a plurality of endless grooves,each of said grooves being of substantially uniform cross-sectionaldimensions and each of said grooves being equidistantly spaced from eachadjacent groove along a line of division of said mold blank, dividingsaid mold blank into segments along said line of division whichintersects each of said endless grooves twice to divide said endlessgrooves into groove segments, and interconnecting divided mold blanksegments and the divided endless groove segments thereof to define atleast one continuous helical molding groove having a plurality ofconvolutions which lie in a generally flat plane.
 2. The method of claim1 in which said mold blank is divided along a line which divides saidendless grooves into equal halves and in which the mold blank segmentscarrying said equal halves are interconnected in abutting contact witheach other along said dividing line to define said continuous helicalmolding groove.
 3. The method of claim 1 in which a mold insert defininggroove segments in a surface thereof is positioned in abutting contactwith said mold blank segments and the groove segments thereof arealigned and interconnected with said mold blank groove segments todefine said continuous helical molding groove.
 4. The method of claim 1in which said mold blank comprises at least two mold segments havingcoplanar surface sections defining said substantially flat surfaceportion, said segments abutting each other prior to forming saidplurality of endless grooves, said mold segments being separated aftergroove forming to divide said plurality of endless grooves into saidgroove segments.
 5. The method of claim 2 in which said interconnecteddivided groove segments define two continuous helical molding grooves.6. A method of making a molding member defining a continuous helicalmolding groove, the convolutions of said helical molding groove lying ina generally flat plane, comprising the steps of providing a mold blankhaving a substantially flat surface portion, forming in said surfaceportion a plurality of concentric circular molding grooves, each of saidmolding grooves being of substantially uniform cross-sectionaldimensions and each of said grooves being equidistantly spaced from eachnext adjacent molding groove, dividing said mold blank into segmentsalong a line of division which intersects each of said concentriccircular molding grooves twice to divide said circular molding groovesinto groove segments, and aligning and interconnecting divided moldblank segments and said divided groove segments to define at least onecoNtinuous helical molding groove having a plurality of convolutionswhich lie in a generally flat plane.
 7. The method of claim 1 in whichprior to the dividing of said mold blank a second plurality of endlessgrooves are formed in said surface portion, two of said second groovesbeing positioned adjacent each of said first plurality of grooves.
 8. Amethod of making a molding member defining a continuous helical moldinggroove the convolutions of which lie in a generally flat plane,comprising the steps of forming a first mold segment defining aplurality of open-ended first groove segments, said first groovesegments being equally spaced from each other at adjacent open ends,forming a second mold segment defining a plurality of open-ended secondgroove segments, said second groove segments being equally spaced fromeach other at adjacent open ends, said spacing being the same as thespacing of adjacent ends of said first groove segments, the distancebetween the ends of a groove segment of the first mold segment beingdifferent from the distance between the ends of a groove segment of saidsecond mold segment, that difference being equal to the spacing betweenadjacent open ends of said groove segments, abutting said mold segments,and aligning the ends of the respective groove segments of said moldsegments, whereby a continuous helical molding having a plurality ofconvolutions is made.
 9. The method of claim 8 wherein a continuoushelical overflow groove is formed adjacent to said continuous helicalmolding groove.